The present invention pertains to a synthetic coating composition, and more particularly to a silicone-cork ablative material.
Ablative materials are used as heat shields to protect space vehicles as they are subjected to high velocity, high temperature conditions during launch and during re-entry to the earth's atmosphere. Such materials need to exhibit good adhesion to the substrate, be flexible enough to provide thermal strain stability, have good thermal stability, and have low thermal conductivity.
Ablative materials in current use may be roughly categorized as either solid materials or cured-in-place coating compositions. Cured-in-place ablative coating compositions may be either low viscosity compositions for a spray application or high viscosity compositions for hand trowel application.
Solid coverings (e.g. cork sheet or ceramic blocks) must be conformed and adhered to the substrate to be protected. Fabrication of a smooth covering from solid ablative materials and removal of the charred covering from the spacecraft after re-entry are difficult, time consuming, and expensive processes.
U.S. Pat. No. 4,837,250 to Headrick et al. illustrates a trowelable ablative coating composition. The composition comprises an epoxy resin, an amide curing agent, glass microspheres, and ground cork.
One problem which exists today is the weight of current thermal protection systems. The materials required to protect a vehicle are relatively heavy, and the more a material weighs, the less payload or weight can be launched or carried. Materials require the capability to protect the applicable surface by virtue of their properties. Most current thermal protection systems are limited to the ablation of the material, and the quantity applied to protect the substrate of the vehicle. This results in the undesirable weight. Furthermore, thicker materials for higher temperature areas add additional weight and further reduce payload capacity.